An example of a video display device that displays a plurality of videos on a single screen is disclosed in Patent Document 1. The video display device that is disclosed in Patent Document 1 switches automatically between displaying videos of two channels and displaying a video of one channel on one screen without inputting a switching signal from outside.
Here, the word “screen” shall be confirmed. For example, in Patent Document 1, the case of displaying videos of two channels on a single screen is called “two-screen” display, while the case of displaying a video of one channel in one screen is called “one-screen” display. That is, the word “screen” is used with the meaning of a display region corresponding to each video signal. On the other hand, “screen” is also used as a word meaning the entire surface that projects an image in a video display device. In this case, a screen would mean each display surface of a video display device. For example, “two screens” ordinarily means two display surfaces of two video display devices. In the present application, the word “screen” is used with the latter meaning, that is, as a word meaning the entire surface that projects an image in a video display device.
As disclosed in Patent Document 1, in the case of displaying the videos of two channels in a single screen, the modes of displaying videos of two channels can be classified into the following two types. The first is a mode that displays videos of two channels in an overlapping manner. The second is a mode that displays the videos of two channels side by side without overlapping. Here, referring to FIG. 21, a description shall be given for a display example of the latter display mode, that is, the mode of displaying the videos of two channels side by side on one screen. FIG. 21 is a diagram that describes a display example of the mode that displays the videos of two channels side by side on one screen.
In the example shown in FIG. 21, a partition line 920 is set in the middle of the screen of a video display device 902, and two videos by video signals of two channels are displayed separately on the left side and right side of the partition line 920. That is, based on a left-side video signal and a right-side video signal that are video signals of two channels, a video 921 by the left-side video signal is displayed on the left side of the partition line 920, and a video 922 by the right-side video signal is displayed on the right side of the partition line 920. In the example shown in FIG. 21, in the case of the original resolution of the left-side video signal being greater than half of the resolution of the screen of the video display device 902, the video 921 that is displayed on the left side of the partition line 920 becomes a reduced video. Also, in the example shown in FIG. 21, in the case of the original resolution of the right-side video signal being less than half of the resolution of the screen of the video display device 902, the video 922 that is displayed on the right side of the partition line 920 is a video of the same resolution as the original resolution. In the example shown in FIG. 21, the video 921 of the left side is shown having been reduced.
Note that the word “resolution” is used in the two senses of: the sense of fineness of the pixels (also called dots, pixels and the like); and the sense of total number of pixels. In the case of the former, resolution is expressed by dot pitch or dpi (dots per inch). In the case of the latter, resolution is a value that is expressed in the form of the product of the number of dots in the horizontal direction of the screen and the number of dots in the vertical direction, that is, “number of dots in horizontal direction”×“number of dots in vertical direction”. In the present application, the latter meaning, that is, expressing resolution as the total pixel number, is employed. In this case, resolution is also called screen resolution.